I normally use gVim for editing, but I sometimes use vim when remotely connecting to my machine.
When I have a file opened in gVim and it has changed from outside (e.g. new updates from repository), gVim offers to reload it.
However when such a thing happens with Vim, it does nothing until you try to save the file. It just warns you that file has changed, but does not offer to reload it.
It there a setting to make Vim's behavior match gVim?
This is done using an auto command called FileChangedShell. I'm too new to post links, but your best bet would be to read the autocmd part of the vim documentation (Google for that)
but the gist is to set something like the following line in your vimrc
:au FileChangedShell * echo "Warning: File changed on disk"